Prosecutors in Thailand have indicted former Thai Prime Minister Abhisit Vejjajiva and his ex-deputy on murder charges related to a deadly crackdown on anti-government protests.

About 90 people died and nearly 1,900 were wounded in the series of street clashes in central Bangkok in 2010.

The violence was between mostly unarmed "Red Shirt" demonstrators and security forces firing live rounds.

Mr Abhisit, who is now the opposition leader, and his former deputy Suthep Thaugsuban ordered security forces to reclaim areas of the capital, the office of Thailand's Attorney General said.

"Evidence shows that their orders caused others to carry out murder and attempted murder," Nanthasak Poonsuk, a spokesman for the Attorney General, said. The opposition criticised the move as an attempt to pressure it to support a controversial amnesty bill that could allow fugitive former premier Thaksin Shinawatra to return from self-imposed exile.

The case will be referred to a criminal court which will decide whether to put the pair on trial.

Mr Abhisit insists he is innocent and has described the accusations against him as politically motivated.

Human rights groups such as Human Rights Watch have welcomed moves to prosecute the pair.